In our work, we investigate efficient usage of TTCN-3 based test components in the emerging field of distributed performance testing of communicating systems. TTCN-3 is a high level formal specification language used ...
详细信息
ISBN:
(纸本)9781424407385
In our work, we investigate efficient usage of TTCN-3 based test components in the emerging field of distributed performance testing of communicating systems. TTCN-3 is a high level formal specification language used for the specification of Abstract Test Suites (ATSs) suitable for various testing purposes mainly in telecommunication systems testing. A TTCN3 based test system may consist of several distributedparallel Test Components (PTCs) and can be executed utilizing diverse hardware platforms. Our aim is to aid development of load tests by establishing a framework, while collecting best practices at the same time, that can be used to execute tests over mixed hardware resources efficiently. We, mainly focus on automated and dynamic deployment of load test components implemented purely in TTCN-3. Also, the deployment method takes test system load into account by monitoring the participating workstations' behavior on-line. A potential test method is shown that can be used for testing server applications using low-cost or even legacy hardware as the platform for distributed test components. A basic scenario involving SMTP (Simple Mail Transfer Protocol) service testing is presented as an example.
In this paper, we designed and implemented a High-Level Abstract parallel Programming Platform that relieves the programmer from all the hassle involved in parallel programming. That is, what is requested from the pro...
详细信息
ISBN:
(纸本)9781424417513
In this paper, we designed and implemented a High-Level Abstract parallel Programming Platform that relieves the programmer from all the hassle involved in parallel programming. That is, what is requested from the programmer is only to specify the program is a suitable form that hides many of the hardware features. All the parallel processes control, that were very challenging, are hence assumed by the platform itself To date, only three parallel programming approaches were suggested in the literature: Implicit, explicit and systematic parallel programming. Among the paradigms that are part of the third approach, we preferred to use the GAMMA formalism as a backbone for our implementation mainly for two reasons: First, it uses an unstructured data set, which has the benefit of reducing the data dependency to its lowest possible level and second, the program correctness can be easily demonstrated. A GAMMA program is generally defined as a pair of condifion, action, where the elements that fulfill the condition are substituted with the product of the action. The program is naturally and systematically executed in parallel. However, to date, no attempt was made to provide a physical implementation of the GAMMA formalism. As an application for our implemented platform, we suggested to parallelize some classical GIS image decomposition problems. The obtained results showed that, in addition to the ease and abstract way of parallel programming, an almost linear speedup is achieved.
Dataflow programming has received increasing attention in the age of multicore computing. Modular and concurrent dataflow program descriptions enable highly automated approaches for design space exploration, optimizat...
详细信息
ISBN:
(纸本)9781479975914
Dataflow programming has received increasing attention in the age of multicore computing. Modular and concurrent dataflow program descriptions enable highly automated approaches for design space exploration, optimization and deployment of applications. A great advance in dataflow programming has been the recent introduction of the RVC-CAL language. Having been standardized by the ISO, the RVC-CAL dataflow language provides a solid basis for the development of tools, design methodologies and design flows. This paper proposes a novel design flow for mapping RVC-CAL dataflow programs to highly parallel execution platforms. Through the proposed design flow the programmer can describe an application in the RVC-CAL language and map it to multi-and many-core platforms for efficient execution. The functionality and efficiency of the proposed approach is demonstrated by a parallel implementation of a video processing application and a run-time reconfigurable filter for telecommunications. Experiments are performed on a multicore platform with up to 16 cores, and the results show that for high-performance applications the proposed design flow provides up to 4x higher throughput than the state-of-the-art approach in multicore execution of RVC-CAL programs.
The integration of mobile/portable computing devices within existing data networks can be expected to spawn distributedapplications that execute on mobile hosts (MHs). For reliability, it is vital that the global sta...
详细信息
The integration of mobile/portable computing devices within existing data networks can be expected to spawn distributedapplications that execute on mobile hosts (MHs). For reliability, it is vital that the global state of such applications be checkpointed from time to time. A global checkpoint consists of a set of local checkpoints, one per participant. This paper first identifies the problems in recording a consistent global state of mobile distributedapplications. The location of a MH within the static network varies with time and therefore, a MH will first need to be located ('searched') in order to obtain its local checkpoint. Moreover, MHs often (voluntarily) disconnect from the network;a disconnected MH is not reachable from the rest of the network. This means that a (disconnected) MH may not be available to provide its local checkpoint. Lastly, a MH is not equipped with stable storage;disk space at a MH is not considered stable due to vulnerability of MHs to loss, theft and physical damage. Therefore, an alternative stable repository is required to save local checkpoints of MHs. This paper presents a checkpointing algorithm for MHs that satisfies these constraints.
The proceedings contains 33 papers from the internationalconference on Virtual Systems and Multimedia (VSMM 39;97). Topics discussed include: collaborative virtual environments;modeling and rendering for virtual en...
详细信息
The proceedings contains 33 papers from the internationalconference on Virtual Systems and Multimedia (VSMM '97). Topics discussed include: collaborative virtual environments;modeling and rendering for virtual environments;virtual heritage;telerobotics and virtual reality devices;virtual humans;distributed multimedia;image/video processing for multimedia;and virtual reality system applications.
In this paper, we present algorithms for in-situ calibration of sensor networks for distributed detection in the parallel fusion architecture. The wireless sensors act as local detectors and transmit preliminary detec...
详细信息
ISBN:
(纸本)9781424415014
In this paper, we present algorithms for in-situ calibration of sensor networks for distributed detection in the parallel fusion architecture. The wireless sensors act as local detectors and transmit preliminary detection results to an access point or fusion center for decision combining. In order to implement an optimal fusion center, both the performance parameters of each local detector (i.e., its probability of false alarm and probability of miss) as well as the wireless channel conditions must be known. However, in real-world applications these statistics may be unknown or vary in time. In our approach, the fusion center receives a collection of labeled samples from the sensor nodes after deployment of the network and calibrates the impact of individual sensors on the final detection result. In the case that local sensor decisions are independent, we employ maximum likelihood parameter estimation techniques, whereas in the case of arbitrarily correlated sensor Outputs, we use the method of kernel smoothing. The obtained fusion rules are both asymptotically optimal and show good performance for finite sample sizes.
Many parallel join algorithms have been proposed so far but most of which are developed focused on minimizing the disk I/O and CPU costs. The communication cost, however, is also an important factor that can significa...
详细信息
Many parallel join algorithms have been proposed so far but most of which are developed focused on minimizing the disk I/O and CPU costs. The communication cost, however, is also an important factor that can significantly affect the join processing performance in multiprocessor systems. In this paper we propose an efficient parallel join algorithm, called Cube-Robust, for hypercube multicomputers. The proposed algorithm is developed based on the observation that the size ratio of two relations to be joined is the dominant factor in the communication cost. We develop the analytic cost model for the proposed join algorithm. The performance comparisons show that the Cube-Robust join algorithm works better than others proposed earlier in a wide range of size ratios.
Modern embedded applications often require high computational power and, on the other hand, fulfilment of real-time constraints and high level of resilience. Simulink is one widely used tool for model-based developmen...
详细信息
ISBN:
(纸本)9781479984909
Modern embedded applications often require high computational power and, on the other hand, fulfilment of real-time constraints and high level of resilience. Simulink is one widely used tool for model-based development of embedded software. In this paper, we focus on the derivation of parallel programs from Simulink models and real-time resilient execution of derived implementations on a many-core platform. The main contribution is a fault-tolerance (FT) mechanism that prevents data loss when the platform is dynamically reconfigured to mask failures of individual cores. Finally, we evaluate the proposed solutions on an industrial case study using a commercially available NoC-based platform. The evaluation shows that the proposed FT mechanism has a marginal overhead.
Over the past decades, distributed computing has been gaining popularity. It provides more computing power and memory space for parallelapplications. On the other hand, such applications fight back and challenge the ...
详细信息
ISBN:
(纸本)0769522424
Over the past decades, distributed computing has been gaining popularity. It provides more computing power and memory space for parallelapplications. On the other hand, such applications fight back and challenge the architectures of the distributed systems for more efficiency. To face the challenge, a Key Messaging (KM) scheme was proposed to realize the optimization of communication at a system architecture level in our previous papers. The contribution of KM is that it performs the optimization in both the underlying communication system and high level application model. The performance of an application is always determined by its critical path. Currently, messages along the critical path can be easily blocked by non-critical path messages, which degrades the performance. To solve this problem, KM provides an algorithm to identify the critical-path messages and optimizes them by introducing a prioritized protocol layer Thus, these messages will be served first before any low priority messages. Shorter processing time for the messages results in faster completion time of the critical path.
Network operators gradually open their interfaces to formerly hidden services which fosters the development of a new class of mobile applications that take into account context information such as the users location. ...
详细信息
ISBN:
(纸本)9781424417964
Network operators gradually open their interfaces to formerly hidden services which fosters the development of a new class of mobile applications that take into account context information such as the users location. However, this development also raises problems. Especially the lack of protection of privacy in location-based services. In this work we propose a service architecture that is aimed at overcoming some of the shortages of currently existing context-aware applications that make use of network providers services. It makes use of a novel privacy enhancing mechanism that is based on the notion of pseudonyms that are applicable even on mobile devices with restrictions regarding resources like memory or processing power. Due to the flexibility of the privacy enhancing mechanism many different kinds of applications are conceivable. The most important aspect in this respect is the highly postulated pay-as-you-go model. To illustrate our approach we demonstrate a transport ticket application that is extended by location-tracking functionality and discuss a management module which allows 3(rd) party application developers to test complex interaction patterns even for a huge number of notional users prior to the realization of full mobile applications and by confirming obligatory requirements regarding data and privacy protection legislation.
暂无评论